Light emitting diode (LED) lighting systems are becoming more prevalent as replacements for existing lighting systems. LED systems are an example of solid state lighting (SSL) and have advantages over traditional lighting solutions such as incandescent and fluorescent lighting because they use less energy, are more durable, operate longer, can be combined in multi-color arrays that can be controlled to deliver virtually any color light, and generally contain no lead or mercury. A solid state lighting system may take the form of a lighting unit, light fixture, light bulb, or a “lamp.”
An LED lighting system may include, for example, a packaged light emitting device including one or more light emitting diodes (LEDs), which may include inorganic LEDs, which may include semiconductor layers forming p-n junctions and/or organic LEDs (OLEDs), which may include organic light emission layers. Light perceived as white or near-white may be generated by a combination of red, green, and blue (“RGB”) LEDs. Output color of such a device may be altered by separately adjusting supply of current to the red, green, and blue LEDs. Another method for generating white or near-white light is by using a lumiphor such as a phosphor. Still another approach for producing white light is to stimulate phosphors or dyes of multiple colors with an LED source. Many other approaches can be taken.
LED units often include some type of optical element or elements to allow for localized mixing of colors, collimate light, or provide a particular light pattern. Sometimes the optical element also serves as an envelope or enclosure for the electronics and/or the LEDs. A power supply can be included in the system along with the LEDs or LED packages and the optical components. The heat generated by the LEDs can raise the temperature of the power supply components, and/or vice versa, and the resulting temperature increase must be taken into account in the system design. A heatsink, heat pipe and/or other heat removal or dissipation elements are also often needed to cool the LEDs and/or power supply in order to maintain appropriate operating temperature for the LEDs and any other electronics in the system.